Organic electroluminescent compounds and organic electroluminescent device comprising the same

ABSTRACT

The present disclosure relates to organic electroluminescent compounds and an organic electroluminescent device comprising the same. The organic electroluminescent compound according to the present disclosure may be comprised in a light-emitting layer or an electron buffer layer, and is effective to produce an organic electroluminescent device having low driving voltage, excellent current and power efficiencies, and significantly improved operative lifespan.

CLAIM OF BENEFIT OF PRIOR APPLICATION

This application claims priority under 35 U.S.C. § 120 from U.S. patentapplication Ser. No. 15/744,884 filed Jan. 15, 2018, which is theNational Stage Entry of PCT/KR2016/006853, filed Jun. 27, 2016, both ofwhich are incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present disclosure relates to organic electroluminescent compoundsand an organic electroluminescent device comprising the same.

BACKGROUND ART

An electroluminescent device (EL device) is a self-light-emitting devicewhich has advantages in that it provides a wider viewing angle, agreater contrast ratio, and a faster response time. The first organic ELdevice was developed by Eastman Kodak, by using small aromatic diaminemolecules, and aluminum complexes as materials for forming alight-emitting layer [Appl. Phys. Lett. 51, 913, 1987].

An organic EL device (OLED) is a device changing electrical energy tolight by applying electricity to an organic electroluminescent material,and generally has a structure comprising an anode, a cathode, and anorganic layer between the anode and the cathode. The organic layer of anorganic EL device may be comprised of a hole injection layer, a holetransport layer, an electron blocking layer, a light-emitting layer(which comprises host and dopant materials), an electron buffer layer, ahole blocking layer, an electron transport layer, an electron injectionlayer, etc., and the materials used for the organic layer arecategorized by their functions in hole injection material, holetransport material, electron blocking material, light-emitting material,electron buffer material, hole blocking material, electron transportmaterial, electron injection material, etc. In the organic EL device,due to an application of a voltage, holes are injected from the anode tothe light-emitting layer, electrons are injected from the cathode to thelight-emitting layer, and excitons of high energies are formed by arecombination of the holes and the electrons. By this energy, organicluminescent compounds reach an excited state, and light emission occursby emitting light from energy due to the excited state of the organicluminescent compounds returning to a ground state.

The most important factor determining luminous efficiency in an organicEL device is light-emitting materials. A light-emitting material musthave high quantum efficiency, and high electron and hole mobility, andthe formed light-emitting material layer must be uniform and stable.Light-emitting materials are categorized into blue, green, and redlight-emitting materials dependent on the color of the light emission,and additionally yellow or orange light-emitting materials. In addition,light-emitting materials can also be categorized into host and dopantmaterials according to their functions. Recently, the development of anorganic EL device providing high efficiency and long lifespan is anurgent issue. In particular, considering EL characteristic requirementsfor a middle or large-sized panel of OLED, materials showing bettercharacteristics than conventional ones must be urgently developed. Thehost material, which acts as a solvent in a solid state and transfersenergy, needs to have high purity and a molecular weight appropriate forvacuum deposition. Furthermore, the host material needs to have highglass transition temperature and high thermal degradation temperature toachieve thermal stability, high electro-chemical stability to achieve along lifespan, ease of forming an amorphous thin film, good adhesion tomaterials of adjacent layers, and non-migration to other layers.

Also, the electron buffer layer can improve the problem that whenexposed to a high temperature in the process of the manufacture ofpanels, the current properties of the device may be changed in thedevices, thereby lowering the light-emitting luminance, and thus theproperties of compounds comprised in the electron buffer layer areimportant.

Japanese patent application laid-open No. 2001-23777 discloses anorganic electroluminescent device using a phenanthrene compound, inwhich a 5-membered heteroaryl containing nitrogen is condensed with themiddle benzene ring of the phenanthrene backbone, as a host material.

DISCLOSURE OF THE INVENTION Problems to be Solved

The organic electroluminescent device comprising the compound disclosedin Japanese patent application laid-open No. 2001-23777 shows excellentcolor purity characteristics of blue, but needs for improving drivingvoltage, current efficiency, and operative lifespan of the organicelectroluminescent device have still remained.

In this regard, the present inventors have found that low drivingvoltage, excellent efficiency, and a significantly improved operativelifespan of an organic electroluminescent device could be achieved byusing a phenanthrene compound, in which a 5-membered heteroaryl iscondensed with a side benzene ring of the phenanthrene backbone, as ahost or in the electron buffer layer.

The object of the present disclosure is to provide organicelectroluminescent compounds being effective to produce an organicelectroluminescent device having low driving voltage, excellent currentand power efficiencies, and significantly improved operative lifespan.

Solution to Problems

The present inventors found that the above objective can be achieved byan organic electroluminescent compound represented by the followingformula 1:

wherein

-   -   X₁ represents —N═, —NR₇—, —O—, or —S—;    -   Y₁ represents —N═, —NR₈—, —O—, or —S—;    -   with the provisos that when X₁ represents —N═, then Y₁        represents —NR₈—, —O—, or —S—, and when X₁ represents —NR₇—,        then Y₁ represents —N═, —O—, or —S—, with the provisos that X₁        and Y₁ are not simultaneously —O—; X₁ and Y₁ are not        simultaneously —S—; X₁ and Y₁ are not —O—and —S—, respectively;        and X₁ and Y₁ are not —S— and —O—, respectively;    -   R₁ represents a substituted or unsubstituted (C6-C30)aryl, or a        substituted or unsubstituted (3- to 30-membered)heteroaryl;    -   R₂ to R₄, R₇, and R₈, each independently, represent hydrogen,        deuterium, a halogen, a cyano, a substituted or unsubstituted        (C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, a        substituted or unsubstituted (3- to 30-membered)heteroaryl, a        substituted or unsubstituted (C3-C30)cycloalkyl, a substituted        or unsubstituted (C1-C30)alkoxy, a substituted or unsubstituted        tri(C1-C30)alkylsilyl, a substituted or unsubstituted        di(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted        (C1-C30)alkyldi(C6-C30)arylsilyl, a substituted or unsubstituted        tri(C6-C30)arylsilyl, a substituted or unsubstituted mono- or        di-(C1-C30)alkylamino, a substituted or unsubstituted mono- or        di- (C6-C30)arylamino, or a substituted or unsubstituted        (C1-C30)alkyl(C6-C30)arylamino; or are linked to an adjacent        substituent(s) to form a substituted or unsubstituted, mono- or        polycyclic, (C3-C30) alicyclic or aromatic ring, whose carbon        atom(s) may be replaced with at least one heteroatom selected        from nitrogen, oxygen, and sulfur;    -   a represents 1; b and c, each independently, represent 1 or 2; d        represents an integer of 1 to 4; and    -   the heteroaryl contains at least one heteroatom selected from B,        N, O, S, Si, and P.

Effects of the Invention

By using the organic electroluminescent compound of the presentdisclosure in a light-emitting layer as a host or in an electron bufferlayer, efficiency, and lifespan of the organic electroluminescent deviceare significantly improved compared to the conventional organicelectroluminescent compounds. In particular, the organicelectroluminescent compound of the present disclosure shows propertiesmore suitable to the current trend of increasing demand for highresolution by maintaining high efficiency at high luminance and having asignificantly improved lifespan.

EMBODIMENTS OF THE INVENTION

Hereinafter, the present disclosure will be described in detail.However, the following description is intended to explain thedisclosure, and is not meant in any way to restrict the scope of thedisclosure.

The present disclosure relates to an organic electroluminescent compoundrepresented by formula 1, an organic electroluminescent materialcomprising the organic electroluminescent compound, and an organicelectroluminescent device comprising the organic electroluminescentcompound.

The organic electroluminescent compound of formula 1 may be representedby any one of the following formulae 2 to 4:

In formulae 1 to 4, R₁ represents a substituted or unsubstituted(C6-C30)aryl, or a substituted or unsubstituted (3- to30-membered)heteroaryl; preferably, a substituted or unsubstituted(C6-C30)aryl, or a substituted (5- to 25-membered)heteroaryl; and morepreferably, a substituted or unsubstituted (C6-C30)aryl, or asubstituted (5- to 20-membered)heteroaryl. For example, R₁ may be anunsubstituted phenyl, an unsubstituted biphenyl, an unsubstitutednaphthyl, a fluorenyl substituted with methyl, a benzofluorenylsubstituted with methyl, a carbazolyl substituted with phenyl, abenzocarbazolyl substituted with phenyl, an indolocarbazolyl substitutedwith phenyl, an unsubstituted dibenzofuranyl, an unsubstituteddibenzothiophenyl, a spiro[fluorene-fluorene], or aspiro[fluorene-benzofluorene].

In formulae 1 to 4, R₂ to R₉, each independently, represent hydrogen,deuterium, a halogen, a cyano, a substituted or unsubstituted(C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, asubstituted or unsubstituted (3- to 30-membered)heteroaryl, asubstituted or unsubstituted (C3-C30)cycloalkyl, a substituted orunsubstituted (C1-C30)alkoxy, a substituted or unsubstitutedtri(C1-C30)alkylsilyl, a substituted or unsubstituteddi(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted(C1-C30)alkyldi(C6-C30)arylsilyl, a substituted or unsubstitutedtri(C6-C30)arylsilyl, a substituted or unsubstituted mono- ordi-(C1-C30)alkylamino, a substituted or unsubstituted mono- or di-(C6-C30)arylamino, or a substituted or unsubstituted(C1-C30)alkyl(C6-C30)arylamino; or are linked to an adjacentsubstituent(s) to form a substituted or unsubstituted, mono- orpolycyclic, (C3-C30) alicyclic or aromatic ring, whose carbon atom(s)may be replaced with at least one heteroatom selected from nitrogen,oxygen, and sulfur; preferably, each independently, hydrogen, asubstituted or unsubstituted (C6-C25)aryl, a substituted orunsubstituted (3- to 25-membered)heteroaryl, or a substituted orunsubstituted mono- or di- (C6-C25)arylamino; or are linked to anadjacent substituent(s) to form a substituted or unsubstituted, mono- orpolycyclic, (C3-C25) alicyclic or aromatic ring, whose carbon atom(s)may be replaced with at least one heteroatom selected from nitrogen,oxygen, and sulfur; more preferably, each independently, hydrogen, asubstituted or unsubstituted (C6-C20)aryl, a substituted orunsubstituted (5- to 25-membered)heteroaryl, or a substituted orunsubstituted di(C6-C18)arylamino; or are linked to an adjacentsubstituent(s) to form a substituted or unsubstituted, mono- orpolycyclic, (C3-C25) alicyclic or aromatic ring, whose carbon atom(s)may be replaced with at least one heteroatom selected from nitrogen andsulfur; and the heteroaryl contains at least one heteroatom selectedfrom B, N, O, S, Si, and P. For example, R₂ to R₄, each independently,may be selected from the group consisting of hydrogen, a substitutedphenyl, a substituted triazinyl, a substituted pyrimidinyl, asubstituted or unsubstituted carbazolyl, a substituted benzocarbazolyl,an unsubstituted dibenzocarbazolyl, and a substituted or unsubstituteddiphenylamino, or may be linked to an adjacent substituent(s) to form asubstituted indene ring, or a substituted benzothiophene ring. Also, forexample, R₅ and R₆, each independently, may be selected from the groupconsisting of hydrogen, a substituted or unsubstituted phenyl, asubstituted or unsubstituted carbazolyl, an unsubstitutedbenzocarbazolyl, and an unsubstituted dibenzocarbazolyl, or may belinked to an adjacent substituent(s) to form an unsubstituted benzenering, an indole ring substituted with phenyl, a benzoindole ringsubstituted with phenyl, an indene ring substituted with methyl, or abenzoindene ring substituted with methyl.

In formulae 1 to 4, X₁ represents —N═, —NR₇—, —O—, or —S—; Y₁ represents—N═, —NR₈—, —O—, or —S—; with the provisos that when X₁ represents —N═,then Y₁ represents —NR₈—, —O—, or —S—, and when X₁ represents —NR₇—,then Y₁ represents —N═, —O—, or —S—, with the provisos that X₁ and Y₁are not simultaneously —O—; X₁ and Y₁ are not simultaneously —S—; X₁ andY₁ are not —O— and —S—, respectively; and X₁ and Y₁ are not-S— and —O—,respectively. Herein, R₇ and R₈ may be a substituted phenyl.

In formulae 1 to 4, a represents 1; and b and c, each independently,represent 1 or 2, preferably 1.

In formula 1, d represents an integer of 1 to 4, preferably 1 or 2.

In formulae 2 to 4, L₁ represents a single bond, a substituted orunsubstituted (C6-C30)arylene, or a substituted or unsubstituted (3- to30-membered)heteroarylene; preferably, a single bond, or a substitutedor unsubstituted (C6-C18)arylene; more preferably, a single bond, or anunsubstituted (C6-C12)arylene; and for example, a single bond, or anunsubstituted phenyl.

In formula 2, X₂ to X₄, each independently, represent —N— or —CR₉—;preferably, at least one of X₂ to X₄ represents —N—; and morepreferably, at least two of X₂ to X₄ represent —N—. Herein, R₉ may behydrogen.

In formula 2, Ar₁ and Ar₂, each independently, represent a substitutedor unsubstituted (C6-C30)aryl, or a substituted or unsubstituted (3- to30-membered)heteroaryl; preferably, a substituted or unsubstituted(C6-C25)aryl, or a substituted or unsubstituted (3- to25-membered)heteroaryl; more preferably, an unsubstituted (C6-C20)aryl,or a substituted or unsubstituted (5- to 20-membered)heteroaryl; and forexample, an unsubstituted phenyl, an unsubstituted biphenyl, anunsubstituted naphthyl, an unsubstituted dibenzothiophenyl, a fluorenylsubstituted with methyl, a benzofluorenyl substituted with methyl, acarbazolyl substituted with phenyl, a benzocarbazolyl substituted withphenyl, or an unsubstituted benzonaphthothiophenyl.

In formulae 2 to 4, e represents an integer of 1 to 3, preferably 1 or2.

In formulae 3 and 4, Z represents a single bond, or a substituted orunsubstituted (C1-C6)alkylene; and preferably, a single bond.

In formula 3, n represents 0 or 1; and f and g, each independently,represent an integer of 1 to 4, preferably 1 or 2.

In formula 4, n represents 0 or 1, preferably 1; g represents an integerof 1 to 4, preferably 1 or 2; and h represents an integer of 1 to 3,preferably 1 or 2.

In formula 4, W represents —NR₁₀—, —O—, —S—, or —CR₁₁R₁₂—, preferably—NR₁₀—.

In formula 4, R₁₀ represents a substituted or unsubstituted(C6-C30)aryl, or a substituted or unsubstituted (3- to30-membered)heteroaryl; preferably, a substituted or unsubstituted(C6-C20)aryl; more preferably, an unsubstituted (C6-C18)aryl; and forexample, an unsubstituted phenyl.

In formula 4, R₁₁ and R₁₂, each independently, represent a substitutedor unsubstituted (C1-C30)alkyl, a substituted or unsubstituted(C6-C30)aryl, or a substituted or unsubstituted (3- to30-membered)heteroaryl; preferably, each independently, represent asubstituted or unsubstituted (C1-C20)alkyl; more preferably, eachindependently, represent an unsubstituted (C1-C15)alkyl; and forexample, an unsubstituted methyl.

Herein, “(C1-C30)alkyl” is meant to be a linear or branched alkyl having1 to 30 carbon atoms constituting the chain, in which the number ofcarbon atoms is preferably 1 to 20, more preferably 1 to 10, andincludes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,tert-butyl, etc.; “(C3-C30)cycloalkyl” is a mono- or polycyclichydrocarbon having 3 to 30 ring backbone carbon atoms, in which thenumber of carbon atoms is preferably 3 to 20, more preferably 3 to 7,and includes cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.;“(C6-C30)aryl(ene)” is a monocyclic or fused ring derived from anaromatic hydrocarbon having 6 to 30 ring backbone carbon atoms, in whichthe number of carbon atoms is preferably 6 to 20, more preferably 6 to15, and includes phenyl, biphenyl, terphenyl, naphthyl, binaphthyl,phenylnaphthyl, naphthylphenyl, fluorenyl, phenylfluorenyl,benzofluorenyl, dibenzofluorenyl, phenanthrenyl, phenylphenanthrenyl,anthracenyl, indenyl, triphenylenyl, pyrenyl, tetracenyl, perylenyl,chrysenyl, naphthacenyl, fluoranthenyl, etc.; and “(3- to 30-membered)heteroaryl(ene)” is an aryl having 3 to 30 ring backbone atoms,preferably 5 to 25 ring backbone atoms, including at least one,preferably 1 to 4 heteroatoms selected from the group consisting of B,N, O, S, Si, and P; may be a monocyclic ring, or a fused ring condensedwith at least one benzene ring; may be partially saturated; may be oneformed by linking at least one heteroaryl or aryl group to a heteroarylgroup via a single bond(s); and includes a monocyclic ring-typeheteroaryl including furyl, thiophenyl, pyrrolyl, imidazolyl, pyrazolyl,thiazolyl, thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl,oxadiazolyl, triazinyl, tetrazinyl, triazolyl, tetrazolyl, furazanyl,pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, etc., and a fusedring-type heteroaryl including benzofuranyl, benzothiophenyl,isobenzofuranyl, dibenzofuranyl, dibenzothiophenyl, benzimidazolyl,benzothiazolyl, benzoisothiazolyl, benzoisoxazolyl, benzoxazolyl,isoindolyl, indolyl, benzoindolyl, indazolyl, benzothiadiazolyl,quinolyl, isoquinolyl, cinnolinyl, quinazolinyl, quinoxalinyl,carbazolyl, benzocarbazolyl, dibenzocarbazolyl, phenoxazinyl,phenanthridinyl, benzodioxolyl, etc. Furthermore, “halogen” includes F,Cl, Br, and I.

Herein, “substituted” in the expression “substituted or unsubstituted”means that a hydrogen atom in a certain functional group is replacedwith another atom or group, i.e. a substituent. The substituents of thesubstituted alkyl(ene), the substituted aryl(ene), the substitutedheteroaryl(ene), the substituted cycloalkyl, the substituted alkoxy, thesubstituted trialkylsilyl, the substituted dialkylarylsilyl, thesubstituted alkyldiarylsilyl, the substituted triarylsilyl, thesubstituted mono- or di-alkylamino, the substituted mono- ordi-arylamino, the substituted alkylarylamino, and the substituted mono-or polycyclic, alicyclic or aromatic ring in R₁ to R₁₂, L₁, Ar₁, Ar₂,and Z of formulae 1 to 4, each independently, are at least one selectedfrom the group consisting of deuterium; a halogen; a cyano; a carboxyl;a nitro; a hydroxyl; a (C1-C30)alkyl; a halo(C1-C30)alkyl; a(C2-C30)alkenyl; a (C2-C30)alkynyl; a (C1-C30)alkoxy; a(C1-C30)alkylthio; a (C3-C30)cycloalkyl; a (C3-C30)cycloalkenyl; a (3-to 7-membered)heterocycloalkyl; a (C6-C30)aryloxy; a (C6-C30)arylthio; a(3- to 30-membered)heteroaryl unsubstituted or substituted with(C1-C6)alkyl or (C6-C30)aryl; a (C6-C30)aryl unsubstituted orsubstituted with cyano, (3- to 30-membered)heteroaryl, or mono- or di-(C6-C30)arylamino; a tri(C1-C30)alkylsilyl; a tri(C6-C30)arylsilyl; adi(C1-C30)alkyl(C6-C30)arylsilyl; a (C1-C30)alkyldi(C6-C30)arylsilyl; anamino; a mono- or di- (C1-C30)alkylamino; a mono- or di-(C6-C30)arylamino; a (C1-C30)alkyl(C6-C30)arylamino; a(C1-C30)alkylcarbonyl; a (C1-C30)alkoxycarbonyl; a (C6-C30)arylcarbonyl;a di(C6-C30)arylboronyl; a di(C1-C30)alkylboronyl; a(C1-C30)alkyl(C6-C30)arylboronyl; a (C6-C30)aryl(C1-C30)alkyl; and a(C1-C30)alkyl(C6-C30)aryl; preferably, each independently, are at leastone selected from the group consisting of a (C1-C6)alkyl; a (C6-C30)arylunsubstituted or substituted with (3- to 30-membered)heteroaryl ordi(C6-C30)arylamino; a (3- to 30-membered)heteroaryl unsubstituted orsubstituted with (C1-C6)alkyl or (C6-C30)aryl; and a mono- or di-(C6-C30)arylamino; or are linked to an adjacent substituent(s) to form asubstituted or unsubstituted, mono- or polycyclic, (C5-C30) alicyclic oraromatic ring, whose carbon atom(s) may be replaced with at least oneheteroatom selected from nitrogen, oxygen, and sulfur; and for example,an unsubstituted methyl, a phenyl unsubstituted or substituted withcarbazolyl or diphenylamino, an unsubstituted biphenyl, an unsubstitutednaphthyl, a fluorenyl substituted with methyl, a benzofluorenylsubstituted with methyl, an unsubstituted a dibenzothiophenyl, acarbazolyl unsubstituted or substituted with phenyl, a benzocarbazolylunsubstituted or substituted with phenyl, an unsubstituteddibenzocarbazolyl, a pyrimidinyl substituted with phenyl, anunsubstituted benzonaphthothiophenyl, or an unsubstituteddi(C6-C12)arylamino, or are linked to an adjacent substitutent(s) toform an indole ring substituted with phenyl, a benzoindole ringsubstituted with phenyl, an unsubstituted benzene ring, a benzindenering substituted with methyl, or an indene ring substituted with methyl.

The organic electroluminescent compound represented by formula 1includes the following compounds, but is not limited thereto:

The present disclosure further provides an organic electroluminescentmaterial comprising the organic electroluminescent compound of formula1, and an organic electroluminescent device comprising the organicelectroluminescent material.

The organic electroluminescent material can be comprised of the organicelectroluminescent compound of the present disclosure alone, or canfurther include conventional materials generally used in organicelectroluminescent materials.

The organic electroluminescent device of the present disclosure maycomprise a first electrode, a second electrode, and at least one organiclayer between the first and second electrodes. The organic layer maycomprise at least one organic electroluminescent compound of formula 1.

One of the first and second electrodes may be an anode, and the othermay be a cathode. The organic layer may comprise a light-emitting layer,and may further comprise at least one layer selected from a holeinjection layer, a hole transport layer, an electron transport layer, anelectron buffer layer, an electron injection layer, an interlayer, ahole blocking layer, and an electron blocking layer.

The organic electroluminescent compound of formula 1 of the presentdisclosure can be comprised in the light-emitting layer as a hostmaterial or in an electron buffer layer. Preferably, the light-emittinglayer may comprise at least one dopant. If necessary, another compoundbesides the organic electroluminescent compound of formula 1 may becomprised as a second host material.

Another embodiment of the present disclosure provides an electron buffermaterial comprising the organic electroluminescent compound of formula1, and an organic electroluminescent device comprising the electronbuffer material.

The organic electroluminescent device of the present disclosurecomprises a first electrode; a second electrode opposing the firstelectrode; a light-emitting layer between the first electrode and thesecond electrode; and an electron transport zone and an electron bufferlayer between the light-emitting layer and the second electrode. Theelectron buffer layer may comprise a compound represented by formula 1.When using the above compound, the driving voltage, the efficiency, andthe lifespan of the device can be improved.

The dopant used in the present disclosure is preferably at least onephosphorescent dopant. The phosphorescent dopant material used for theorganic electroluminescent device of the present disclosure is notlimited, but may be preferably selected from metallated complexcompounds of iridium (Ir), osmium (Os), copper (Cu), and platinum (Pt),more preferably selected from ortho-metallated complex compounds ofiridium (Ir), osmium (Os), copper (Cu), and platinum (Pt), and even morepreferably ortho-metallated iridium complex compounds.

The dopant to be comprised in the organic electroluminescent device ofthe present disclosure may be selected from the group consisting of thecompounds represented by the following formulae 10 to 12.

wherein L_(d) is selected from the following structures:

R₁₀₀ represents hydrogen, a substituted or unsubstituted (C1-C30)alkyl,or a substituted or unsubstituted (C3-C30)cycloalkyl;

R₁₀₁ to R₁₀₉ and R₁₁₁ to R₁₂₃, each independently, represent hydrogen,deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl, asubstituted or unsubstituted (C3-C30)cycloalkyl, a cyano, or asubstituted or unsubstituted (C1-C30)alkoxy; and adjacent substituentsof R₁₂₀ to R₁₂₃ may be linked to each other to form a substituted orunsubstituted fused ring, e.g., a substituted or unsubstitutedquinoline;

R₁₂₄ to R₁₂₇, each independently, represent hydrogen, deuterium, ahalogen, a substituted or unsubstituted (C1-C30)alkyl, or a substitutedor unsubstituted (C6-C30)aryl; and adjacent substituents of R₁₂₄ to R₁₂₇may be linked to each other to form a substituted or unsubstituted fusedring, e.g., a substituted or unsubstituted fluorene, a substituted orunsubstituted dibenzothiophene, or a substituted or unsubstituteddibenzofuran;

R₂₀₁ to R₂₁₁, each independently, represent hydrogen, deuterium, ahalogen, a substituted or unsubstituted a (C1-C30)alkyl, a substitutedor unsubstituted (C3-C30)cycloalkyl, or a substituted or unsubstituted(C6-C30)aryl; and adjacent substituents of R₂₀₁ to R₂₁₁ may be linked toeach other to form a substituted or unsubstituted fused ring, e.g., asubstituted or unsubstituted dibenzofuran, or a substituted orunsubstituted dibenzothiophene;

r and s, each independently, represent an integer of 1 to 3; where r ors is an integer of 2 or more, each of R₁₀₀ may be the same or different;and

t represents an integer of 1 to 3.

Specifically, the phosphorescent dopant materials include the following:

The organic electroluminescent device of the present disclosure mayfurther comprise, in addition to the compound of formula 1, at least onecompound selected from the group consisting of arylamine-based compoundsand styrylarylamine-based compounds.

In the organic electroluminescent device of the present disclosure, theorganic layer may further comprise, in addition to the compound offormula 1, at least one metal selected from the group consisting ofmetals of Group 1, metals of Group 2, transition metals of the 4^(th)period, transition metals of the 5^(th) period, lanthanides, and organicmetals of the d-transition elements of the Periodic Table, or at leastone complex compound comprising the metal. The organic layer may furthercomprise one or more additional light-emitting layers and a chargegenerating layer.

In addition, the organic electroluminescent device of the presentdisclosure may emit white light by further comprising at least onelight-emitting layer, which comprises a blue, a red, or a greenelectroluminescent compound known in the field, besides the compound ofthe present disclosure. If necessary, it may further comprise a yellowor an orange light-emitting layer.

In the organic electroluminescent device of the present disclosure,preferably, at least one layer (hereinafter, “a surface layer”) may beplaced on an inner surface(s) of one or both electrode(s), selected froma chalcogenide layer, a metal halide layer, and a metal oxide layer.Specifically, a chalcogenide (includes oxides) layer of silicon oraluminum is preferably placed on an anode surface of anelectroluminescent medium layer, and a metal halide layer or a metaloxide layer is preferably placed on a cathode surface of anelectroluminescent medium layer. Such a surface layer provides operationstability for the organic electroluminescent device. Preferably, thechalcogenide includes SiO_(x)(1≤X≤2), AlO_(x)(1≤X≤1.5), SiON, SiAlON,etc.; the metal halide includes LiF, MgF₂, CaF₂, a rare earth metalfluoride, etc.; and the metal oxide includes Cs₂O, Li₂O, MgO, SrO, BaO,CaO, etc.

In the organic electroluminescent device of the present disclosure, amixed region of an electron transport compound and a reductive dopant,or a mixed region of a hole transport compound and an oxidative dopantmay be placed on at least one surface of a pair of electrodes. In thiscase, the electron transport compound is reduced to an anion, and thusit becomes easier to inject and transport electrons from the mixedregion to an electroluminescent medium. Furthermore, the hole transportcompound is oxidized to a cation, and thus it becomes easier to injectand transport holes from the mixed region to the electroluminescentmedium. Preferably, the oxidative dopant includes various Lewis acidsand acceptor compounds, and the reductive dopant includes alkali metals,alkali metal compounds, alkaline earth metals, rare-earth metals, andmixtures thereof. A reductive dopant layer may be employed as a chargegenerating layer to prepare an electroluminescent device having two ormore light-emitting layers and emitting white light.

In order to form each layer of the organic electroluminescent device ofthe present disclosure, dry film-forming methods such as vacuumevaporation, sputtering, plasma, and ion plating methods, or wetfilm-forming methods such as ink jet printing, nozzle printing, slotcoating, spin coating, dip coating, and flow coating methods can beused.

When using a wet film-forming method, a thin film can be formed bydissolving or diffusing materials forming each layer into any suitablesolvent such as ethanol, chloroform, tetrahydrofuran, dioxane, etc. Thesolvent can be any solvent where the materials forming each layer can bedissolved or diffused, and where there are no problems in film-formationcapability.

Hereinafter, the organic electroluminescent compounds of the presentdisclosure, the preparation method thereof, and the properties of thedevice comprising the compounds will be explained in detail withreference to the representative compounds of the present disclosure.

Example 1: Preparation of Compound C-24

1) Preparation of Compound 1-1

After introducing compound A (CAS: 1044146-16-8, 36 g, 124 mmol),4-chloro-2-formylbenzene boronic acid (25.2 g, 136 mmol),tetrakis(triphenylphosphine)palladium (5.7 g, 5.0 mmol), sodiumcarbonate (33 g, 150 mmol), toluene (600 mL), ethanol (150 mL), anddistilled water (150 mL) into a reaction vessel, the mixture was stirredfor 3 hours at 140° C. After completing the reaction, the precipitatedsolid was washed with distilled water and methanol. The obtainedcompound 1-1 was used in the next reaction without any furtherpurification.

2) Preparation of Compound 1-2

After introducing compound 1-1 (45.6 g, 130 mmol),(methoxymethyl)triphenylphosphonium chloride (74.3 g, 217 mmol), andtetrahydrofuran (1500 mL) into a reaction vessel, the mixture wasstirred for 5 minutes. Potassium tert-butoxide (1M in THF, 220 mL) wasthen slowly added dropwise to the mixture at 0° C. The temperature ofthe mixture was slowly raised, and the mixture was stirred at roomtemperature for 3 hours. After completing the reaction by addingdistilled water to the reaction solution, an organic layer was extractedwith ethyl acetate. The extracted organic layer was dried with magnesiumsulfate, and the solvent was removed therefrom using a rotaryevaporator. Thereafter, the remaining product was purified by columnchromatography to obtain compound 1-2 (48 g, 97%).

3) Preparation of Compound 1-3

After introducing compound 1-2 (44.8 g, 119 mmol), Eaton's reagent (4.5mL), and chlorobenzene (600 mL) into a reaction vessel, the mixture wasrefluxed for 2 hours. After completing the reaction, the mixure wascooled to room temperature, and an organic layer was extracted withmethylene chloride (MC). After drying the extracted organic layer withmagnesium sulfate, the solvent was removed by using a rotary evaporator.Thereafter, the obtained product was purified by column chromatographyto obtain compound 1-3 (36.3 g, 89%).

4) Preparation of Compound C-24

After introducing compound 1-3 (8 g, 23 mmol), compound B (CAS:1060735-14-9, 9.5 g, 23 mmol), tris(dibenzylidyneacetone)dipalladium (1g, 1.16 mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (s-phos)(0.95 g, 2.31 mmol), sodium tert-butoxide (4.5 g, 46.3 mmol), ando-xylene (150 mL) into a reaction vessel, the mixture was stirred for 3hours at 170° C. After completing the reaction, the mixture was addeddropwise to methanol, and the obtained solid was filtered. The obtainedsolid was purified by column chromatography to obtain compound C-24 (8.7g, 68%).

Example 2: Preparation of Compound C-1

1) Preparation of Compound 2-1

After introducing compound C (10 g, 29 mmol), bis(pinacolato)diborane(8.8 g, 34.8 mmol), tris(dibenzylidyneacetone)dipalladium (1.3 g, 1.45mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (s-phos) (1.2 g,2.9 mmol), potassium acetate (8.5 g, 87 mmol), and 1,4-dioxane (150 mL)into a reaction vessel, the mixture was stirred for 3 hours at 140° C.After completing the reaction, the mixure was cooled to roomtemperature, and an organic layer was extracted with ethyl acetate.After drying the extracted organic layer with magnesium sulfate, thesolvent was removed by using a rotary evaporator. Thereafter, theobtained product was purified by column chromatography to obtaincompound 2-1 (10.4 g, 82%).

2) Preparation of Compound C-1

After introducing compound 2-1 (10 g, 23.8 mmol),2-chloro-4,6-diphenyltriazine (CAS: 3842-55-5, 6.4 g, 23.8 mmol),tris(dibenzylidyneacetone)dipalladium (1 g, 1.16 mmol),2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (s-phos) (1 g, 2.31mmol), sodium tert-butoxide (4.5 g, 46.3 mmol), and o-xylene (150 mL)into a reaction vessel, the mixture was stirred for 3 hours at 170° C.After completing the reaction, the mixture was added dropwise tomethanol, and the obtained solid was filtered. The obtained solid waspurified by column chromatography to obtain compound C-1 (8.2 g, 55%).

Example 3: Preparation of Compound C-17

After introducing compound C (8 g, 23.1 mmol), compound D (CAS:1448296-00-1, 7.7 g, 23.1 mmol), tetrakis(triphenylphosphine)palladium(1.4 g, 1.19 mmol), potassium carbonate (8.2 g, 60 mmol), toluene (90mL), ethanol (30 mL), and distilled water (30 mL) into a reactionvessel, the mixture was stirred for 3 hours at 140° C. After completingthe reaction, the precipitated solid was washed with distilled water andmethanol. The obtained compound was purified by column chromatography toobtain compound C-17 (8.7 g, 77%).

Example 4: Preparation of Compound C-39

1) Preparation of Compound 3-1

After introducing compound E (CAS: 913835-76-4, 40 g, 212.7 mmol),benzaldehyde (27 g, 255.29 mmol), sodium cyanide (10.4 g, 212.7 mmol),and N,N-dimethylformamide (DMF) (1000 mL) into a reaction vessel, themixture was stirred for 3 hours at 100° C. The reaction solution cooledto room temperature was extracted with ethyl acetate. The obtainedcompound 3-1 was used in the next reaction without any furtherpurification.

2) Preparation of Compound 3-2

After introducing compound 3-1 (35 g, 128 mmol),4-chloro-2-formylbenzene boronic acid (26 g, 141 mmol),tetrakis(triphenylphosphine)palladium (6 g, 5.1 mmol), sodium carbonate(34 g, 320 mmol), toluene (600 mL), ethanol (150 mL), and distilledwater (150 mL) into a reaction vessel, the mixture was stirred for 3hours at 140° C. After completing the reaction, the precipitated solidwas washed with distilled water and methanol. The obtained compound 3-2was used in the next reaction without further purification.

3) Preparation of Compound 3-3

After introducing compound 3-2 (19 g, 56.9 mmol),(methoxymethyl)triphenylphosphonium chloride (29.3 g, 85.4 mmol), andtetrahydrofuran (500 mL) into a reaction vessel, the mixture was stirredfor 5 minutes. Potassium tert-butoxide (1M in THF, 85 mL) was thenslowly added dropwise to the mixture at 0° C. The temperature of themixture was slowly raised, and the mixture was stirred at roomtemperature for 3 hours. After completing the reaction by addingdistilled water to the reaction solution, an organic layer was extractedwith ethyl acetate. The obtained organic layer was dried with magnesiumsulfate, and the solvent was removed therefrom using a rotaryevaporator. Thereafter, the remaining product was purified by columnchromatography to obtain compound 3-3 (16.4 g, 80%).

4) Preparation of Compound 3-4

After introducing compound 3-3 (14.4 g, 39.8 mmol), Eaton's reagent (1.4mL), and chlorobenzene (200 mL) into a reaction vessel, the mixture wasrefluxed for 2 hours. After completing the reaction, the mixure wascooled to room temperature, and an organic layer was extracted withmethylene chloride (MC). After drying the extracted organic layer withmagnesium sulfate, the solvent was removed by using a rotary evaporator.Thereafter, the obtained product was purified by column chromatographyto obtain compound 3-4 (11.1 g, 79%).

5) Preparation of Compound C-39

After introducing compound 3-4 (4 g, 12.1 mmol), compound B (CAS:1060735-14-9, 4.9 g, 12.1 mmol), tris(dibenzylidyneacetone)dipalladium(0.5 g, 0.61 mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl(s-phos) (0.5 g, 1.21 mmol), sodium tert-butoxide (2.33 g, 24.3 mmol),and o-xylene (100 mL) into a reaction vessel, the mixture was stirredfor 3 hours at 170° C. After completing the reaction, the mixture wasadded dropwise to methanol, and the obtained solid was filtered. Theobtained solid was purified by column chromatography to obtain compoundC-39 (8.7 g, 47%).

Example 5: Preparation of Compound C-49

1) Preparation of Compound 2-1

Compound 2-1 was prepared in the same manner as described in Example 2.

2) Preparation of Compound C-49

After introducing compound 2-1 (4.5 g, 10 mmol),2-chloro-4,6-diphenylpyrimidine (CAS: 2915-16-4, 2.7 g, 10 mmol),tetrakis(triphenylphosphine)palladium (0.47 g, 0.4 mmol), potassiumcarbonate (3.6 g, 26 mmol), toluene (50 mL), ethanol (13 mL), anddistilled water (13 mL) into a reaction vessel, the mixture was stirredfor 4 hours at 120° C. After completing the reaction, the mixture wasadded dropwise to methanol, and the obtained solid was filtered. Theobtained solid was purified by column chromatography to obtain compoundC-49 (4.5 g, 73%).

Example 6: Preparation of Compound C-75

1) Preparation of Compound 4-1

After introducing compound F (7.2 g, 21.8 mmol), bis(pinacolato)diborane(6.6 g, 26.2 mmol), tris(dibenzylidyneacetone)dipalladium (1.0 g, 1.1mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (s-phos) (0.89 g,2.2 mmol), potassium acetate (6.4 g, 65 mmol), and 1,4-dioxane (150 mL)into a reaction vessel, the mixture was stirred for 3 hours at 140° C.After completing the reaction, the mixure was cooled to roomtemperature, and an organic layer was extracted with ethyl acetate.After drying the extracted organic layer with magnesium sulfate, thesolvent was removed by using a rotary evaporator. Thereafter, theobtained product was purified by column chromatography to obtaincompound 4-1 (5.2 g, 57%).

2) Preparation of Compound C-75

After introducing compound 4-1 (5.2 g, 12.3 mmol),2-chloro-4,6-diphenylpyrimidine (CAS: 2915-16-4, 3.3 g, 12.3 mmol),tetrakis(triphenylphosphine)palladium (0.71 g, 0.62 mmol), potassiumcarbonate (4.2 g, 30 mmol), toluene (60 mL), ethanol (20 mL), anddistilled water (20 mL) into a reaction vessel, the mixture was stirredfor 4 hours at 120° C. After completing the reaction, the mixture wasadded dropwise to methanol, and the obtained solid was filtered. Theobtained solid was purified by column chromatography andrecrystallization to obtain compound C-75 (5.3 g, 82%).

Example 7: Preparation of Compound C-87

1) Preparation of Compound G

Compound G was prepared in the same manner as the preparation ofcompound 3-2 described in Example 4, except for using5-chloro-2-formylboronic acid instead of 4-chloro-2-formylbenzeneboronic acid.

2) Preparation of Compound 5-1

After introducing compound G (15 g, 45.5 mmol), bis(pinacolato)diborane(13.9 g, 54.6 mmol), tris(dibenzylidyneacetone)dipalladium (1.6 g, 1.8mmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (s-phos) (0.9 g,3.64 mmol), potassium acetate (13 g, 136 mmol), and 1,4-dioxane (350 mL)into a reaction vessel, the mixture was stirred for 3 hours at 140° C.After completing the reaction, the mixure was cooled to roomtemperature, and an organic layer was extracted with ethyl acetate.After drying the extracted organic layer with magnesium sulfate, thesolvent was removed by using a rotary evaporator. Thereafter, theobtained product was purified by column chromatography to obtaincompound 5-1 (20 g, 99%).

3) Preparation of Compound C-87

After introducing compound 5-1 (10 g, 22.7 mmol),2-chloro-4,6-diphenylpyrimidine (CAS: 2915-16-4, 5.5 g, 20.6 mmol),tetrakis(triphenylphosphine)palladium (1.2 g, 1.0 mmol), potassiumcarbonate (7.1 g, 56 mmol), toluene (90 mL), ethanol (30 mL), anddistilled water (30 mL) into a reaction vessel, the mixture was stirredfor 4 hours at 120° C. After completing the reaction, the mixture wasadded dropwise to methanol, and the obtained solid was filtered. Theobtained solid was purified by column chromatography andrecrystallization to obtain compound C-87 (5.5 g, 51%).

Example 8: Preparation of Compound C-88

After introducing compound 5-1 (10 g, 23.7 mmol),2-chloro-4,6-diphenyltriazine (CAS: 3842-55-5, 5.8 g, 21.6 mmol),tetrakis(triphenylphosphine)palladium (1.2 g, 1.0 mmol), potassiumcarbonate (7.5 g, 59 mmol), toluene (90 mL), ethanol (30 mL), anddistilled water (30 mL) into a reaction vessel, the mixture was stirredfor 4 hours at 120° C. After completing the reaction, the mixture wasadded dropwise to methanol, and the obtained solid was filtered. Theobtained solid was purified by column chromatography andrecrystallization to obtain compound C-88 (5.7 g, 50%).

Example 9: Preparation of Compound C-45

1) Preparation of Compound 9-1

After introducing compound 7-bromo-2-phenyl-benzoxazole (37 g, 135mmol), 4-chloro-2-formylbenzene boronic acid (25 g, 135 mmol),tetrakis(triphenylphosphine)palladium (7.8 g, 6.7 mmol), sodiumcarbonate (35 g, 338 mmol), toluene (680 mL), ethanol (170 mL), anddistilled water (170 mL) into a reaction vessel, the mixture was stirredfor 3 hours at 130° C. After completing the reaction, the precipitatedsolid was washed with distilled water and methanol. The obtainedcompound was purified by column chromatography to obtain compound 9-1(26 g, 60%).

2) Preparation of Compound 9-2

After introducing compound 9-1 (26 g, 80.2 mmol),(methoxymethyl)triphenylphosphonium chloride (41 g, 120 mmol), andtetrahydrofuran (800 mL) into a reaction vessel, the mixture was stirredfor 5 minutes. Potassium tert-butoxide (1 M in THF, 120 mL) was thenslowly added dropwise to the mixture at 0° C. The temperature of themixture was slowly raised, and the mixture was stirred at roomtemperature for 3 hours. After completing the reaction by addingdistilled water to the reaction solution, an organic layer was extractedwith ethyl acetate. The extracted organic layer was dried with magnesiumsulfate, and the solvent was removed therefrom using a rotaryevaporator. Thereafter, the remaining product was purified by columnchromatography to obtain compound 9-2 (25 g, 87%).

3) Preparation of Compound 9-3

After introducing compound 9-2 (25 g, 70.2 mmol), Eaton's reagent (3mL), and chlorobenzene (350 mL) into a reaction vessel, the mixture wasrefluxed for 2 hours. After completing the reaction, the mixure wascooled to room temperature, and an organic layer was extracted withmethylene chloride (MC). After drying the extracted organic layer withmagnesium sulfate, the solvent was removed by using a rotary evaporator.Thereafter, the obtained product was purified by column chromatographyto obtain compound 9-3 (13 g, 56%).

4) Preparation of Compound 9-4

After introducing compound 9-3 (13 g, 39 mmol),bis(pinacolato)dibororane (12 g, 47 mmol),tris(dibenzylidyneacetone)dipalladium (1.8 g, 1.9 mmol),2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (s-phos) (1.6 g, 3.9mmol), potassium acetate (11 g, 118 mmol), and 1,4-dioxane (330 mL) intoa reaction vessel, the mixture was stirred for 4 hours at 130° C. Aftercompleting the reaction, the mixure was cooled to room temperature, andan organic layer was extracted with ethyl acetate. After drying theextracted organic layer with magnesium sulfate, the solvent was removedby using a rotary evaporator. Thereafter, the obtained product waspurified by column chromatography to obtain compound 9-4 (13 g, 81%).

5) Preparation of Compound C-45

After introducing compound 9-4 (13 g, 31 mmol),2-chloro-4,6-diphenyltriazine (8 g, 30 mmol),tetrakis(triphenylphosphine)palladium (1.7 g, 1.5 mmol), potassiumcarbonate (10 g, 75 mmol), toluene (140 mL), ethanol (35 mL), anddistilled water (35 mL) into a reaction vessel, the mixture was stirredfor 4 hours at 130° C. After completing the reaction, the precipitatedsolid was washed with distilled water and methanol. Thereafter, theobtained product was purified by column chromatography to obtaincompound C-45 (7.7 g, 49%).

Example 10: Preparation of Compound C-100

After introducing compound 9-4 (3 g, 7.1 mmol),2-(3-bromophenyl)-4,6-diphenyl-1,3,5-triazine (CAS: 864377-31-1, 3.04 g,7.8 mmol), tetrakis(triphenylphosphine)palladium (0.41 g, 0.36 mmol),sodium carbonate (1.9 g, 17.8 mmol), toluene (24 mL), ethanol (6 mL),and distilled water (6 mL) into a reaction vessel, the mixture wasstirred for 4 hours at 120° C. After completing the reaction, themixture was added dropwise to methanol, and the obtained solid wasfiltered. The obtained solid was purified by column chromatography andrecrystallization to obtain compound C-100 (2.3 g, 54%).

Example 11: Preparation of Compound C-101

After introducing compound 9-4 (3.48 g, 8.3 mmol),2-([1,1′-biphenyl]-4-yl)-4-chloro-6-phenyl-1,3,5-triazine (CAS:1472062-94-4, 3.53 g, 9.1 mmol), tetrakis(triphenylphosphine)palladium(0.48 g, 0.41 mmol), sodium carbonate (2.2 g, 20.7 mmol), toluene (28mL), ethanol (7 mL), and distilled water (7 mL) into a reaction vessel,the mixture was stirred for 5 hours at 120° C. After completing thereaction, the mixture was added dropwise to methanol, and the obtainedsolid was filtered. The obtained solid was purified by columnchromatography and recrystallization to obtain compound C-101 (3.7 g,74%).

The properties of the above synthesized compounds are shown in Table 1below.

TABLE 1 MS/EIMS Yield UV Spectrum PL Spectrum MP Measured CalculatedCompound (%) (in toluene, nm) (in toluene, nm) (° C.) Value Value C-24 68 306 418 240 718.1 717.22 C-1  55 306 426 276 543.2 542.16 C-17  77306 426 276 642.0 641.19 C-39  47 304 400 230 702.1 701.25 C-49  73 362420 279 542.0 541.66 C-75  82 260 392 300 526.1 525.18 C-87  51 296 402278 526.1 525.18 C-88  50 290 427 291 527.1 526.18 C-45  49 345 426 309526.6 526.18 C-100 54 358 401 298 602.7 602.21 C-101 74 324 429 299602.7 602.21

Hereinafter, the luminescent properties of the organicelectroluminescent device comprising the organic electroluminescentcompound of the present disclosure will be explained in detail withreference to the following examples.

Device Example 1: Preparation of an OLED Device Comprising the OrganicElectroluminescent Compounds of the Present Disclosure as a Host

An OLED device was produced by using the organic electroluminescentcompound according to the present disclosure. A transparent electrodeindium tin oxide (ITO) thin film (10 Ω/sq) on a glass substrate for anorganic light-emitting diode (OLED) device (Geomatec) was subjected toan ultrasonic washing with acetone, ethanol, and distilled water,sequentially, and then was stored in isopropanol. The ITO substrate wasthen mounted on a substrate holder of a vacuum vapor depositingapparatus. Compound HI-1 was introduced into a cell of said vacuum vapordepositing apparatus, and then the pressure in the chamber of saidapparatus was controlled to 10⁻⁶ torr. Thereafter, an electric currentwas applied to the cell to evaporate the above-introduced material,thereby forming a first hole injection layer having a thickness of 80 nmon the ITO substrate. Next, compound HI-2 was introduced into anothercell of said vacuum vapor depositing apparatus, and was evaporated byapplying an electric current to the cell, thereby forming a second holeinjection layer having a thickness of 5 nm on the first hole injectionlayer. Compound HT-1 was then introduced into the cell of said vacuumvapor depositing apparatus, and was evaporated by applying an electriccurrent to the cell, thereby forming a first hole transport layer havinga thickness of 10 nm on the second hole injection layer. Compound HT-3was then introduced into another cell of said vacuum vapor depositingapparatus, and was evaporated by applying an electric current to thecell, thereby forming a second hole transport layer having a thicknessof 60 nm on the first hole transport layer. After forming the holeinjection layer and the hole transport layer, a light-emitting layer wasformed thereon as follows: compound C-24 was introduced into one cell ofsaid vacuum vapor depositing apparatus as a host, and compound D-71 wasintroduced into another cell as a dopant. The dopant was deposited in adoping amount of 3 wt % based on the total amount of the host and dopantto form a light-emitting layer having a thickness of 40 nm on the secondhole transport layer. Compound ET-1 and compound EI-1 were thenintroduced into another two cells, and evaporated at a rate of 1:1 toform an electron transport layer having a thickness of 30 nm on thelight-emitting layer. After depositing compound EI-1 as an electroninjection layer having a thickness of 2 nm on the electron transportlayer, an Al cathode having a thickness of 80 nm was deposited byanother vacuum vapor deposition apparatus. Thus, an OLED device wasproduced.

The produced OLED device showed a red emission having a luminance of1,000 cd/m², and a luminous efficiency of 24.4 cd/A at 4.4 V. The timetaken to be reduced to 90% of the luminance, where the early luminanceis 100%, at 5,000 nits and a constant current was 43 hours or more.

Device Example 2: Preparation of an OLED Device Comprising the OrganicElectroluminescent Compounds of the Present Disclosure as a Host

An OLED device was produced in the same manner as in Device Example 1,except for using compound C-1 as a host of the light-emitting material.The produced OLED device showed a red emission having a luminance of1,000 cd/m², and a luminous efficiency of 27.8 cd/A at 6.0 V. The timetaken to be reduced to 90% of the luminance, where the early luminanceis 100%, at 5,000 nits and a constant current was 37 hours or more.

Device Example 3: Preparation of an OLED Device Comprising the OrganicElectroluminescent Compounds of the Present Disclosure as a Host

An OLED device was produced in the same manner as in Device Example 1,except for using the compound C-39 as a host of the light-emittingmaterial. The produced OLED device showed a red emission having aluminance of 1,000 cd/m², and a luminous efficiency of 22.9 cd/A at 4.5V. The time taken to be reduced to 90% of the luminance, where the earlyluminance is 100%, at 5,000 nits and a constant current was 38 hours ormore.

Comparative Device Example 1: Preparation of an OLED Device ComprisingConventional Organic Electroluminescent Compounds

An OLED device was produced in the same manner as in Device Example 1,except for using the following compound K as a host of thelight-emitting material.

The produced OLED device showed a red emission having a luminance of1,000 cd/m², and a luminous efficiency of 14.3 cd/A at 10.0 V. The timetaken to be reduced to 90% of the luminance, where the early luminanceis 100%, at 5,000 nits and a constant current was less than 1 hour.

The invention claimed is:
 1. An organic electroluminescent compoundrepresented by the following formula 3:

wherein X₁ represents —N═, —NR₇—, —O—, or —S—; Y₁ represents —N═, —NR₈—,—O—, or —S—; with the provisos that when X₁ represents —N═, then Y₁represents —O—, or —S—, and when X₁ represents —NR₇—, then Y₁ represents—O—, or —S—, with the provisos that X₁ and Y₁ are not simultaneously—O—; X₁ and Y₁ are not simultaneously —S—; X₁ and Y₁ are not —O— and—S—, respectively; and X₁ and Y₁ are not —S— and —O—, respectively; R₁represents a substituted or unsubstituted (C6-C30)aryl, or a substitutedor unsubstituted (3- to 30-membered)heteroaryl; R₂ represent hydrogen,deuterium, a halogen, a cyano, a substituted or unsubstituted(C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, asubstituted or unsubstituted (3- to 30-membered)heteroaryl, asubstituted or unsubstituted (C3-C30)cycloalkyl, a substituted orunsubstituted (C1-C30)alkoxy, a substituted or unsubstituted tri(C1-C30)alkylsilyl, a substituted or unsubstituteddi(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted(C1-C30)alkyldi(C6-C30)arylsilyl, or a substituted or unsubstitutedtri(C6-C30)arylsilyl; R₃, R₄, R₇ and R₈, each independently, representhydrogen, deuterium, a halogen, a cyano, a substituted or unsubstituted(C1-C30)alkyl, a substituted or unsubstituted (C6-C30)aryl, asubstituted or unsubstituted (3- to 30-membered)heteroaryl, asubstituted or unsubstituted (C3-C30)cycloalkyl, a substituted orunsubstituted (C1-C30)alkoxy, a substituted or unsubstitutedtri(C1-C30)alkylsilyl, a substituted or unsubstituteddi(C1-C30)alkyl(C6-C30)arylsilyl, a substituted or unsubstituted(C1-C30)alkyldi(C6-C30)arylsilyl, a substituted or unsubstitutedtri(C6-C30)arylsilyl, a substituted or unsubstituted mono- or di-(C1-C30)alkylamino, a substituted or unsubstituted mono- or di-(C6-C30)arylamino, or a substituted or unsubstituted(C1-C30)alkyl(C6-C30)arylamino; or are linked to an adjacentsubstituent(s) to form a substituted or unsubstituted, mono- orpolycyclic, (C3-C30) alicyclic or aromatic ring, whose carbon atom(s)may be replaced with at least one heteroatom selected from nitrogen,oxygen, and sulfur; a represents 1; b and c, each independently,represent 1 or 2; d represents an integer of 1 to 4; L₁ represents asingle bond, a substituted or unsubstituted (C6-C30)arylene, or asubstituted or unsubstituted (3- to 30-membered)heteroarylene; Zrepresents a single bond, or a substituted or unsubstituted(C1-C6)alkylene; R₅ and R₆, each independently, have the same definitionas R₃ to R₄; n represents 0 or 1; e represents an integer of 1 to 3; fand g, each independently, represent an integer of 1 to 4; and theheteroaryl contains at least one heteroatom selected from B, N, O, S,Si, and P.
 2. The organic electroluminescent compound according to claim1, wherein the compound represented by formula 3 is selected from thegroup consisting of:


3. An organic electroluminescent device comprising the organicelectroluminescent compound according to claim 1 as a host material.